BV-T3G Microsoft Lumia 650 Replacement Battery 3.8V 2000mAh

Microsoft Lumia 650 / RM-1154 — 3.8V Li-ion Replacement Battery (BV-T3G)

This is a 3.8V, 2000mAh Li-ion cell that replaces the OEM BV-T3G battery in the Microsoft Lumia 650 and RM-1154 variant. It fits the original battery bay without modification and reconnects to the phone's charge IC via the standard flex connector. Dimensions are 95.60 × 43.20 × 4.00mm — same as the factory cell.

• Lumia 650 and RM-1154 compatibility: Both model numbers share the same chassis, connector pinout, and BMS handshake protocol — one cell covers both. The BV-T3G part number is the identifier the charge IC expects regardless of regional variant.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on a Lumia 650 unit, confirmed the BMS accepted the charge IC handshake without fault flags, and verified voltage held steady at 3.8V nominal under screen and modem load.
• Fuel gauge recalibration on first use: After fitting this cell, disable fast charging and run one full discharge-to-charge cycle before resuming normal use. The Lumia 650's fuel gauge IC is calibrated to the old cell's discharge curve — one full cycle lets it relearn the new cell's profile before any high-current charging begins.

Sudden shutdown at 20–30% on the Lumia 650 after a cell swap

A new Li-ion cell has a slightly different voltage-discharge curve than the worn cell the fuel gauge IC was tracking. When the phone hits a voltage point the IC hasn't mapped yet, it can interpret the drop as a critical-low event and shut down — even though charge remains in the cell. This is a calibration gap, not a faulty battery. Run one complete discharge cycle from 100% down to automatic power-off, then charge uninterrupted to 100%. After that cycle, the fuel gauge recalibrates its coulomb counter to the new cell curve and shutdowns at false-low percentages stop.

Phone warm near the battery slot during the first charge cycle

A replacement cell arrives with higher internal impedance than a broken-in cell — this is normal for a fresh lithium-ion cell that hasn't completed any cycles. The charge IC pushes current into that higher-impedance cell, and the resulting power dissipation shows up as warmth around the battery compartment. It's most noticeable in the first one or two charges and settles as the cell's impedance drops after cycling. If the phone stays warm past the third full charge, check that the battery flex connector is fully seated — a loose contact forces the IC to work harder against a higher-resistance path.